Costs were estimated at 144 billion yuan ($23 billion) when construction began in 2009, but they are likely to have run over. South Asia Analysis Group has more:

According to [Chief engineer] Ren, building the line through difficult terrain like in the Qilian Mountain area requires twice as much investment compared with similar high-speed line construction on low-level flat areas...

A senior researcher with the China Academy of Railway Sciences told Xinhua, on condition of anonymity, that it will be difficult to make money from building such a line.

It's more of a political thing, he said. It's more about national defense and ethnic unity.

There already was a non-high-speed-rail connection to Xinjiang, which served more than adequately to transport oil and coal from the distant province.

Finally the new train required a 67km wall to shield against strong winds from the Gobi Desert, which toppled a train in 2007. Due to wind concerns the maximum speed on the line was reduced from 300km per hour to 250km per hour.